Sustainable production of biomass and industrially important secondary metabolites in cell cultures of selfheal ( L.) elicited by silver and gold nanoparticles.

Elicited artificial cultures are gaining more interest due to their uniform biosynthesis of industrially valuable secondary metabolites. In this study, a unique methodology was applied, in which different ratios of gold (Au) and silver (Ag) nanoparticles (NPs) were supplemented to submerge cultures to investigate sustainable production of biomass and antioxidant secondary metabolites. Cell suspension cultures were exposed to Ag and AuNPs alone or different ratios of AgAuNPs (1:2; 1:3; 2:1; 3:1) in combination with NAA. The combination of AgAuNPs (3:1) with NAA enhanced fresh (9.25 g/100 ml) and dry biomass (0.64 g/100 ml) of suspended cells than control (6.67; 0.233 g/100 ml). AuNPs with NAA-augmented media enhanced biomass accumulation in lag, log and stationary phases in a period of 49 days. Furthermore, AgAu (3:1) and AgAuNPs (2:1; 1:2) with NAA enhanced protein contents, peroxidase and superoxide dismutase enzymes. However, maximum phenolics (TPC; 10.61 mg/g-DW) and flavonoids (7.62 mg/g-DW) were observed in cell cultures exposed to a combination of AgAuNPs (1:3) and NAA than control (6.27, 5.49 mg/g-DW). The combination of AgAuNPs (2:1) with NAA enhanced antioxidant activity (87.85%) in cell cultures. This study will help in illuminating the impact of NPs on cultures development and production of natural antioxidants.